Start by peeling and chopping the pineapples.

In a large pot, combine the chopped pineapples and 4 liters of water. Bring it to a boil, then reduce heat and let it simmer for about 30 minutes.

After simmering, strain the mixture using a fine strainer or cheesecloth.

Stir in the cup of sugar and lemon juice until dissolved.

Allow the mixture to cool to room temperature.

Once cooled, sprinkle the active dry yeast over the mixture. Stir gently to incorporate the yeast.

Transfer the mixture to a fermentation vessel and seal it. Let it sit in a cool, dark place for about one week.

After fermentation, carefully siphon the beer into clean bottles, leaving some space at the top. Cap them tightly and let them carbonate for another few days.